[clang][ExtractAPI] Fix quirks in interaction with submodules (#105868)

Extension SGFs require the module system to be enabled in order to discover which module defines the extended external type.
This patch ensures the following:
- Associate symbols with their top level module name, and that only top level modules are considered as modules for emitting extension SGFs.
- Ensure we don't drop macro definitions that came from a submodule. To this end look at all defined macros in `PPCalbacks::EndOfMainFile` instead of relying on `PPCallbacks::MacroDefined` being called to detect a macro definition.

1 files changed, 2 insertions, 2 deletions

diff --git a/clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp b/clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp
index 1bce9c5..030509d 100644
--- a/clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp
+++ b/clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp
@@ -928,8 +928,8 @@ bool SymbolGraphSerializer::traverseObjCCategoryRecord(
     return true;
 
   auto *CurrentModule = ModuleForCurrentSymbol;
-  if (Record->isExtendingExternalModule())
-    ModuleForCurrentSymbol = &ExtendedModules[Record->Interface.Source];
+  if (auto ModuleExtendedByRecord = Record->getExtendedExternalModule())
+    ModuleForCurrentSymbol = &ExtendedModules[*ModuleExtendedByRecord];
 
   if (!walkUpFromObjCCategoryRecord(Record))
     return false;